ALBERT

Notes: . Due to the important role of monoADP-ribosyl transferases in physiological and pathological events, we investigated whether the protozoan parasite Entamoeba histolytica had monoADP-ribosyl transferase activity. Reactions were initiated using amebafree medium as the source of both enzyme and ADP-ribosylation substrate(s) and [32P]NAD+ as source of ADP-ribose. Proteins were analyzed by electrophoresis, and [32P]-labeled proteins were detected by autoradiography. Using the crude extracellular medium, a major labeled product of Mr 37,000 was observed. The yield of this product was reduced markedly using medium from Brefeldin A-treated trophozoites, indicating that the extracellular monoADP-ribosyl transferase and/or its substrate depended on vesicular transport. The labeling of the 37-kDa substrate was dependent on reaction time, temperature, pH, and the ratio of unlabeled NAD+ to [32P]NAD+. After two purification steps, several new substrates were observed, perhaps due to their enrichment. The reaction measured ADP-ribosylation since [14C-carbonyl]NAD+ was not incorporated into ameba substrates and a 75-fold molar excess of ADP-ribose caused no detectable inhibition of the monoADP-ribosyl transferase reaction. On the basis of sensitivity to NH2OH, the extracellular monoADP-ribosyl transferase of E. histolytica may be an arginine-specific enzyme. These results demonstrate the existence in E. histolytica of at least one extracellular monoADP-ribosyl transferase, whose localization depends upon a secretion process.

Notes: : Plums were treated with calcium or heat (45°C) and then stored at 2°C for 28 d. Fruit firmness, ethylene, and CO2 production rates were investigated. The concentrations of endogenous polyamines (free, conjugated-soluble, and cell wall-bound) were also studied. Both treatments improved fruit firmness by increases in Magness-Taylor force and force-deformation ratio, and decreases in flesh deformation. No differences were found in either ethylene or respiration rate production among fruits due to the low storage temperature. Calcium-treating plums increased the conjugated forms of putrescine (conjugated-soluble and cell wall-bound), which are related to higher firmness. Heat-treated plums mainly increased cell wall-bound spermidine, inducing a greater cell wall stability and plum firmness.

Notes: : Apricots (Prunus armeniaca L. cv Mauricio) harvested at commercial ripening stage were treated with putrescine (1 mM), then mechanically damaged with a 25 N force and stored at 10 °C for 6 d. Putrescine treatment increased fruit firmness and reduced the bruising zones caused by the mechanical damage. Putrescine-treated fruits (both damaged and nondamaged) showed different physiological behavior than controls. Color change, weight loss, ethylene emission, and respiration rate were reduced in putrescine-treated fruits. The most remarkable effect of the mechanical damage was the significant increase in spermidine concentrations found after the compression in control apricots, which could be considered as a physiological marker of mechanical damage.

Notes: : This study simulates the conditions in which Botrytis may appear in a modified atmosphere packed horticulture product, such as strawberry, so as to elaborate a predictive model that could allow us to estimate the shelf-life of a contaminated food product in such atmosphere conditions (0 to 40% CO2). The estimated shelf-lives obtained at 18 °C were 92, 164, and 236 h in storage atmospheres of 0, 10, and 20% CO2, respectively, very close to observed values; no growth was observed above 30% CO2. The elaborated predictive model allows us to: (a) control development of this fungi if the food product is maintained in an atmosphere containing more than 20% CO2 and (b) predict the time taken for potential colonies to become visible (3 mm dia) and, thus, cause immediate rejection by consumers.

Notes: : :The nutritional composition and protein efficiency ratio (PER) of raw corn meal and of tortillas prepared by extrusion and nixtamalization processes were determined. Rats were fed with diets containing unprocessed raw corn meal (RCM), tortillas prepared from extruded fresh masa without lime (ET), tortillas made from extruded fresh masa with 0.25% lime content (ETWL), and tortillas made with the traditional nixtamalization method (NT). The ETWL had higher protein (8.50%) and dietary fiber (14.52%) contents than did the NT (8.15% protein and 7.39% dietary fiber). The PER value of the ETWL diet was 14.65% higher (P ≤ 0.05) than that of the RCM diet and equivalent to that of the NT diet.

Notes: : Market increase efforts for tropical fruits have been previously limited by short shelf life. A modified atmosphere packaging (MAP) system for pineapple and mango was developed to increase shelf life of the fruits. Sample preparation consisted of hand-peeling, dicing, blanching, dipping in ascorbic acid and packaging. The treatments were: gas mixture (4% O2, 10% CO2 and 86% N2); vacuum packaging; 100% oxygen, and control. Microbial growth, texture, and color were significantly (P 〈 0.005) different between the gas and other treatments. The gas mixture treatment achieved the longest shelf life. The sensory analysis showed slight difference between fresh and MAP mango and no difference between fresh and MAP pineapple. MAP could be used as a technology to extend the shelf life of mango and pineapple.

Notes: : This study provides data on the total heme and non-heme iron contents in poultry (chicken, turkey), beef, veal, lamb, horse, ostrich, rabbit, and pork meat cuts. The effect of cooking on heme iron content was also studied. Total iron and heme iron contents markedly differed between muscles in poultry. Heme iron in red meats ranged from 72 to 87%. Heme iron in rabbit and pork was 56 and 62% of total iron. Heating decreased heme iron, the severity of the losses depended on cooking methods: in poultry, losses ranged from 22 to 43%; less severe impact was detected in pan-cooked meat, where the losses ranged from 1 to 24%.

Notes: : Isothermal and non-isothermal heat resistance studies were carried out on Bacillus pumilus spores. The non-isothermal study revealed a non-linear behavior of the survivor curve, which was revealed as a tail after an isothermal study. Results indicated that the spores obtained by isolating cells from colonies of the tail section were more heat resistant than the original ones (D104°c= 0.15 and 1.9 min for spores from the original population and from the tail, respectively). Application of the Weibull distribution model to analyze the tail produced good results at the 3 temperatures studied. Nevertheless, when the model was applied to curves having both concave downward and concave upward sections a poor result was obtained, with an accuracy factor greater than 1.

Notes: A histopathological survey of wild and cultured shrimp from the Gulf of Mexico was carried out to determine the prevalence and severity of infectious diseases and parasites, affecting four species of penaeid shrimp (Litopenaeus setiferus, Farfantepenaeus aztecus, F. duorarum, and L. vannamei). Around 60 shrimp were obtained from each of 10 sampling stations during different months in 1999 and 2000. One station was a shrimp culture farm from Tamaulipas State, and nine were wild stations from Tamaulipas (five), Veracruz (one), and Campeche (three) States. Thirty shrimp from each station were used for histological analysis. The remaining shrimp were frozen and kept at −20 C to carry out PCR techniques to determine the presence of white spot syndrome virus (WSSV). Some in situ hybridization analyses were applied to ascertain cases of WSS viral disease. Fresh analysis was carried out in shrimp from only one station for parasite identification. The histopathological survey performed on 688 shrimp showed no evidence of viral diseases. Two shrimp from one station were histologically diagnosed as having presumptive WSSV. Tissues from the same shrimp were processed for in situ hybridization and another 20 samples from the same station were processed to run PCR techniques. In each case, the results were negative. The same PCR procedure was applied to the rest of the frozen samples and none of them showed the presence of the WSSV. No important bacterial infections were observed in any of the wild or cultured shrimp analyzed. Fresh analysis demonstrated the presence of the cestode Prochristianella hispida and the gregarines Cephalolobus penaeus and Nematopsis penaeus. Histological analysis showed that the abundance of P. hispida varied from 7 to 90%, and G1 to G4 grades of severity were observed, with G1 being the most common. Gregarines were commonly observed in the histological slides, with a prevalence varying from 3 to 56% and G1 severity in most cases. Haplosporidan infection was observed in one sample of F. duorarum, which is the first report of this parasite in this host. Two invasive epibionts, the filamentous bacteria Leucothrix sp. and the ciliate Ascophrys sp., were found in four sampled stations. The study showed that in ten stations sampled from 1999 to 2000 in the Gulf of Mexico, shrimp populations had no serious infectious diseases.